I guess my main rememberence of the pasty Sonic titles was that enough though he wasn't as fast as one would say, the levels gave you an ability to not only go fast with very few obsticles to block you, but once your done "blazing thru" you can go back and explore more like a decent platformer.
It had a good flow instead of possible roadblocks of future titles fell over. That's what stuck to me as being faster when compared to Mario titles.